Generating a New High Resolution DTM Product from various Data Sources

This paper discusses two aspects of the new DTM generation project, the product view from the perspective of the owner (Ordnance Survey) and the technical solution for combining DTMs from the system supplier (Inpho). Ordnance Survey (OS) has a long history of providing height information in a national context from both precise geodetic levelling networks and photogrammetrically surveyed contours. The product being discussed here is based on the most recent contour surveys carried out over the period 1970-1983 in support of national mapping series published at 1:10,000 and 1:25,000 scale. Over the life of the product the technical systems used to maintain the data have been updated from analogue capture machines, to analytical and now digital photogrammetry. The most recent development being the purchase of a digital camera. This technology has now come together to create a new height product from both in house data and third party sourced LIDAR. The technical solution to combine the data has been provided by Inpho using the SCOP++ DTM software and the Topographic Data Management system (TopDM) to process the data and place it in a database from which it can be selected for output by accuracy to build the product tiles. This called for some core development work to enhance the system to provide metadata to meet OS business needs and wrapper software to verify and control the input.